An auctioneer is the person who runs an auction. They stand at the front, call out the prices, watch the hands go up, and bang the hammer when something is sold. Their talk is often very fast, in a rising and falling chant that people joke about. You meet the word in news about art, houses, farm sales, and charity nights. It is a job word, fine in newspapers, not slang. Though actually, the auctioneer is not the owner of the things, and not usually the buyer — they are in the middle, paid to sell for someone else. The word can also be a verb: to auctioneer something is to sell it that way. The verb is less common; most people still say sell at auction or auction off.